The electronic spectra of fulleropyrrole derivatives were studied by using INDO/CI methods on the basis of the optimized geometries with AM1 method. It was shown that the exception of the absorption was beyond 400 nm. The nonlinear second-order optical susceptibilities β_μ of the molecules were calculated according to the sum-over states (SOS) formalism. To the studied molecules, the biggest β_μ value is 402.3×10³⁰ esu. Moreover, the relations among the length of conjugate chain, the electronic spectra and the β_μ were studied. The results suggested that β_μ and λ_max values become larger with the increase of the length of conjugate chain. Compared with the derivatives pyrrolo [3',4':1,2][60]fullerene/barbituric acid (C₆₀PY/BA), the corresponding derivatives pyrrolo [3',4':1,2][60]fullerene/sulfur-barbituric acid (C 60PY/S-BA) have bigger β_μ values.

Key words: barbituric acid, [60]fulleropyrrole derivative, electronic spectrum, nonlinear second2order optical property, INDO/CI